When comparing yay vs Conda, the Slant community recommends yay for most people. In the question“What are the best Linux package managers?” yay is ranked 8th while Conda is ranked 16th. The most important reason people chose yay is:
It's written in Go so it is fairly easy to add features or tweak this amazing tool.
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Pros
Pro Easy to add features
It's written in Go so it is fairly easy to add features or tweak this amazing tool.
Pro Intuitive CLI
Yay's commands and output make sense for anyone used to the pacman package manager.
Pro Written in Go
The compiled program is snappy while the source is easy to read.
Pro Available as a precompiled binary
Both yay and yay-bin are in the AUR, the latter of which doesn't require any dependencies or compilation, making installation and updates quick and painless.
Pro Yogurt interactive mode
Write package name without keys [yay <packagename>] to enter interactive mode.
Pro Doesn't rebuild already-installed apps like Trizen

Pro Binary installs
They are fast and reliable as they do not need to compile before installation.

Pro Allows for multiple environments
It is great for developers since you can easily switch between complete environments with different versions of packages, for testing and development.

Pro Open source
Conda is open source and on Github, so if you see something wrong you can fix it and submit a patch.
Cons
Con Written in Go
Running a Go program requires the Go runtime. Go is also a garbage collected language, so the program isn't as responsive as it could be.

Con Doesn't have everything
Conda is relatively new and has a smaller user-base, so the set of packages available is limited.
Con No way to resume downloads
Any download that is canceled or interrupted will have to be started over from the beginning as there is no built in solution for resuming downloads.

Con Installs huge collection of default unneeded libraries
